feat(config): monitor external changes to config.json

Automatically reload configuration if `config.json` is modified externally during runtime.

Author: kh4f

config.go

@@ -3,27 +3,46 @@ package main
 import ("os"; "encoding/json")
 
 type Config struct {
-	MaxTemp     int `json:"maxTemp"`
+	MaxTemp int `json:"maxTemp"`
 	MaxFanOffTemp int `json:"maxFanOffTemp"`
 }
 
 var config = Config{
-	MaxTemp:     60,
+	MaxTemp: 60,
 	MaxFanOffTemp: 40,
 }
 
 const configFile = "config.json"
+var configModTime int64
 
 func loadConfig() {
 	data, err := os.ReadFile(configFile)
 	if err != nil {
 		saveConfig()
-	} else {
-		json.Unmarshal(data, &config)
+		return
 	}
+	json.Unmarshal(data, &config)
+
+	info, err := os.Stat(configFile)
+	if err != nil { return }
+	configModTime = info.ModTime().Unix()
 }
 
 func saveConfig() {
 	data, _ := json.MarshalIndent(config, "", "  ")
 	os.WriteFile(configFile, data, 0644)
+
+	info, err := os.Stat(configFile)
+	if err == nil {
+		configModTime = info.ModTime().Unix()
+	}
+}
+
+func reloadConfigIfChanged() {
+	info, err := os.Stat(configFile)
+	if err != nil { return }
+
+	if info.ModTime().Unix() != configModTime {
+		loadConfig()
+	}
 }

monitor.go

@@ -56,12 +56,15 @@ func destroyADL() {
 
 func start() {
 	for {
+		reloadConfigIfChanged()
+
 		temp, rpm := readGPU()
 		if int(temp) > config.MaxFanOffTemp && rpm == 0 {
 			alert("GPU temperature > " + fmt.Sprintf("%v", config.MaxFanOffTemp) + "°C and fan is not spinning")
 		} else if int(temp) > config.MaxTemp {
 			alert("GPU temperature > " + fmt.Sprintf("%v", config.MaxTemp) + "°C")
 		}
+
 		time.Sleep(10 * time.Second)
 	}
 }